But of course there is more to it than that. If you wanted just one number with which to gauge the health of developed-market capitalism, you’d find it hard to top the greenback’s rate against the yen. It’s not perfect, of course, but, even so, it’s no stretch to see that the economic world is in trouble if Japan’s cash-sodden investors can’t think of anything better to do with their trillions than to keep them idling at home, earning the miserable rates offered there.

At last, it seems, they can, and in numbers big enough to matter, and the U.S. remains their most obvious destination.

According to data from the Ministry of Finance in Tokyo, Japanese investors were net buyers of foreign assets last week, and the week before, too, after a long period of pulling in their horns.

Crucially, Japan’s mighty life insurers have added $4.2 billion to their overseas portfolios in April alone, leading the charge. And, as analysts at UBS put it this morning, these outfits typically boost their foreign holdings through the first half of the fiscal year, so this source of yen weakness could be with us for some time to come.

However, its’ also worth noting that flow the other way is strong too. Foreign investors have loved the Nikkei ever since Kuroda fired his big guns. And a weaker yen will only add to the allure of Japan’s export powerhouses. That said, domestic stock buying by Japanese investors appears to be tapering off now, and inflows to the Nikkei are clearly being swamped for the moment.